Lpg fuel system for internal combustion engines



y 18, 1965 R. BAVERSTOCK 3,184,295

LPG FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Original Filed Oct. 16, 1959 4 Sheets-Sheet 1 INVENTOR. P/C 6 191? BAH 5P5 TOC K y 1965 R. BAVERSTOCK 3,184,295

LPG FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Original Filed Oct. 16, 1959 4 Sheets-Sheet 2 J J03 J04 fie. 6 91 z/aa/o 7A., V4FUPIZ0 -50- FUA'Z 2 M fie. 5.

INVENTOR.

F/C M l/P17 B9 VE/PS 706 K y 1965 R. BAVERSTOCK 3,184,295

LPG FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Original Filed Oct. 16, 1959 4 Sheets-Sheet 3 179 w flag.

J77 J50 J84 175 INVENTOR. RICHARD 5H Vf/PS TOCK BY 4M4 May 18, 1965 R. BAVERSTOCK LPG FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Original Filed Oct. 16, 1959 J77 J90 .raz

- petroleum gas.

11 prevents leakage of fluid through the pipe 10 when United States Patent 3,184,295 LPG FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Richard Baverstock, North Long Beach, Calif., assignor to Imperial Machine Products Co., South Gate, Calif., a corporation of California Original application Oct. 16, 1959, Ser. No. 846,852, now Patent No. 3,123,451, dated Mar. 3, 1964. Divided and this application Oct. 17, 1260, Ser. No. 62,944 6 Claims. (Cl. 48-184) Liquified petroleum gas comprising butane or propane or mixtures thereof is commonly used in vapor form as a fuel for internal combustion engines. It is the general object of this invention to provide an improved fuel system for delivering a combustible mixture of air and vaporized LPG to the intake manifold of an internal combustion engine. Another object of this invention is to provide such an improved system which includes a novel form of vaporizer having a labyrinth passage provided with heated walls, and having means to prevent droplets from being carried along an unheated top wall of the labyrinth passage. Another object is to provide a vaporizer device having novel means for preventing buildup of excessive pressures in the event of ice formation.

This invention is a division of my copending application, Serial No. 846,852, filed October 16, 1959, now U.S. Patent 3,123,451.

Other and more detailed objects and advantages will appear hereinafter.

Referring to the drawings:

FIGURE 1 is a schematic plan view showing components in the system for supplying a combustible mixture of air and liquid petroleum gas to an internal combustion engine.

FIGURE 2 is a sectional elevation showing details of the vaporizer and regulator, the regulator valve being shown in open position.

FIGURE 3 is a plan view showing the device of FIG- URE 2, the upper portion thereof being removed to expose the labyrinth path for vaporizing the fuel.

FIGURE 4 is a sectional plan view taken substantially on the lines 44 as shown in FIGURE 2.

FIGURE 5 is a sectional detail taken substantially on I the lines 55 as shown in FIGURE 2.

FIGURE 6 is an exploded perspective view partly in section showing details of construction of the regulator valve.

FIGURE 7 is a plan view of the regulator diaphragm.

FIGURE 8 is a sectional elevation of the air fuel mixer device and the pressure sensitive device for actuating an electric switch, the parts being shown in closed position.

FIGURE 9 is a sectional view similar to FIGURE 8, the parts being shown in open position.

FIGURE 10 is a sectional plan view taken substantially along the lines 1ll10 as shown in FIGURE 9.

FIGURE 11 is a sectional detail taken substantially on the lines 11-11 as shown in FIGURE 10.

FIGURE 12 is a sectional detail taken substantially on the lines 12-12 as shown in FIGURE 8.

FIGURE 13 is a perspective view showing the fuel valve plug on an enlarged scale.

FIGURE 14 is a perspective view of the air valve member.

FIGURE 15 is a graph showing operation of the device.

Referring to the drawings, the LPG fuel system shown diagrammatically in FIGURE 1 includes a supply pipe 10 leading from a tank (not shown) containing liquified An electrically operated shut-off valve the engine is not running. The pipe 12 connects the shutoff valve 11 with the vaporizer and regulator generally designated 13 which acts to convert liquid fuel to vaporized fuel at a predetermined low pressure. Vaporized fuel passes through the pipe 14 connecting the regulator 13 to the mixer 15. Atmospheric air passing through a conventional air cleaner 16 is delivered to the mixer 15 through the air inlet pipe 17. A combustible mixture of air and vaporized fuel passes downward from the mixer 15 and as shown in FIGURE 8 passes into a flanged tubular member 18 having a conventional throttle valve 19 mounted therein. The lower flange 20 of the member 18 is adapted for connection to the inlet manifold (not shown) of an internal combustion engine.

The regulator generally designated 13 includes a base having inlet opening 26 for connection to the fuel pipe 12. The base 25 has a horizontal passage 27 extending from the inlet 26 and communicating with the vertical passage 28 extending centrally through the seat 29. Parallel upstanding walls 30 and 31 formed integrally on the base 25 define a central cavity 32 therebetween and the valve lever 33 is positioned within this cavity. The valve lever is pivotally supported on a stationary pivot pin 34 passing through aligned apertures 35 and held in place in a groove 36 provided on a post 37 formed integrally with the base 25. This post projects upward between the parallel side flanges of the valve lever 33, and a retainer screw 38 on the post prevents displacement of the pivot shaft 34 from the groove 36. The screw 38 may be installed and removed through the opening between the side flanges of the lever. A resilient pad 46 formed of synthetic rubber or the like is carried on the cross bar 41 of the valve lever 33 in position to contact the seat 29 to prevent liquid flow into the cavity 32 from the fuel passage 28. The pad 40 is preferably cut from an extruded strip, and may be installed or replaced on the cross bar 41 without requiring the use of tools. The rear projecting end of the lever 33 is slotted as shown at 43 to receive the reduced portion 44 of the vertically movable diaphragm shank 45. Disassembly is prevented by means of the cross bar 46 at the extreme lower end of the shank 45.

The walls 30 and 31 are curved as shown at 48, 49, near the rear slotted end of the lever 33 and a central discharge slot 50 separates the curved ends 51 and 52 of the walls 30 and 31. This slot 50 comprises a discharge passage connecting the valve lever cavity 32 with the labyrinth passages 53 and 54. Labyrinth passages 53 and 54 are defined between the smooth outer surfaces of the walls 39 and 31 and the smooth inner surface of the crescent shaped upstanding wall 55 formed integrally on the base 25. Additional labyrinth passages 59 and 66) are defined between the smooth surface 61 of the outer wall 62 and the smooth outer surface 63 of the crescent shaped wall 55. The centrally positioned discharge port 64 communicates with the labyrinth passages 59 and and connects with the threaded socket 65 which receives the threaded end of the pipe 14.

From this description it will be understood that fuel passes into the valve lever cavity 32 from the passageways 2'7 and 23 and then passes through discharge slot 50 and separates into two flow streams. One passes through labyrinth passages 53 and 59 to the discharge port 64 and the other passes through labyrinth passages 54 and 6t) to the same discharge port 64.

The bottom surfaces of the labyrinth passages are formed by the base member 25 and the upper surfaces are formed by the porous member 66 confined between the circular cover plate 67 and the upper ends of the walls 39, 31, 55 and 62. The cover plate 67 is mounted within a circular bore 68 provided in the upper portion of the base member 25. This cover plate is clamped in position by means of the bonnet 69 which also clamps the outer periphery of the flexible diaphragm 70 to the base member 25. Threaded fastenings 71 connect the bonnet 69 to the base member 25 and extend throughapertured ears 72 provided on the diaphragm 79.

The diaphragm post 45 is provided with a cylindrical section 74 terminating in ,a flange 75. The upper surface of this flange 75 forms an abutment 77. The lower surface of the diaphragm 70 rests on this abutment and the hollow projection 78 extends through the central aperture of the diaphragm and through a similar aperture is placed in communication with the-outlet 64 to insure that the pressure of vaporized fuelat'the outlet remains substantially constant over a major portion of the range At high rates of flow, pressure in the cavity 32 maybe higher-than at the outlet 64, due to pressure drop 'throu'gh'the tortuous passages; However, the pressure at the outlet 64 remains at 2 p.s.i. in a particular installation as shown by the graph of FIGURE for in the back-up plate 79. The end of the projection 78 the range from 5 vacuum to vacuum. Forfull load operation of the engine, that is, in the range from 5" vacuum to 0 the pressure at" the outlet; 64 may be increased above 2 p.s.i., as describedbe'lowi Means areprovided for raising the pressure at the outlet f64'whenever the suction pressure in the intake'manifold of the engine falls below a predetermine'd value,

for example, 5" of'r'nercury, as shown on the chart of FEGURE 15. This means includes a diaphragm 100 clamped between the bonnet 69 and the cap 101 by means the opening 83 in the plate 67. The porousdisk 66, prej vents the washer 81' from dropping into the valve lever cavity 32. The central opening. 83 is large enough-to allow the flange 75 of the'diaphragm shank to pass freelytherethrough.

plunger. as

of threaded fastenings 102. A plunger- 103 secured to the diaphragm 100' and back-up plate 104 passes loosely through opening 105 in the abutment 91 of the bonnet 69.

A' coil spring 106 encircles'the-plunger and extendsfrom the abutment 91'1to a: shoulder 107 provided on the Whenever the engine ;is operating above 5 inches of vacuum suction pressure, this pressure as communicated to the chamber 108- act above the diaphragm The tortuous or labyrinth paths provided for the fuel in its course from the seatopening 28 to thedischarge 1 port 64 not only actto maintain liquid dropletsin contact with the walls b y'centrifugal action but also provide sufficient contactsurface area to introduce the required heat into the fuel so that it leaves the outlet"port 64 in fully vaporized condition without entrainment of liquid droplets.- The walls defining the labyrinth passages'are heated by means of 'hot water which circulates within channels formed internally of'the walls. Thus, hot water,

which may be obtained from the cooling system of the ,engine isintroduced into the base25 through the threaded opening 90. This water passes through channels; 91, 92,

93 in the Walls 62, 55, 31 and lit) respectively and emerges 1 surface. I impedeprogress of the liquid droplets being carried along at the threaded discharge connection 94. Experience has 1 shown that a portion of the fuel .is vaporized at the-time it passesfrom the valve lever cavity 32 through slot 50 into the passages 53 and 54. A'majo'r portion has'been vaporized by the time the fuel enters the labyrinth passages 59 and60 and all of the fuel is'in vaporized form when it leaves the base 25 through the discharge port 64.

The pressure of the vaporized fuel'at the'outlet 64 is communicated to the space above the circular plate, 67 and below the diaphragm 70 through the opening .84. Atmospheric pressure exists in the chamber 88 above the diaphragm 70, since the bonnet 69 is provided with aperture 89 which is open to atmosphere. A coilspring 90 engages under the stationary abutment 91 of the. bon

net 69 and acts against the back-up plate79 restingpn the upper surface ofthe diaphragm 70. The force of the spring plus-the force produced by the atmospheric pressure acting over the upper surface of the diaphragmtend to move the diaphragm downward into contact with the stationary circular plate 67. (Pressure of vaporized fuel adjacent the outlet 64 acts against the underside of the diaphragm in opposition'to the force ofthe spring and the force developed by the atmospheric pressure. When the pressure of the vaporized fuel reaches apredetermined magnitude, for example, 2 pounds per square inch, the diaphragm 70 is raised against the force .of the f spring 90, thereby lifting the slotted end 43 of the lever 33 and enclosing the resilient pad against theseat .29.

When the pressure of vaporized fuel adjacent thev outlet 64 fallsbelow thepredetermined value of pressure intensity, the diaphragm '70moves down, thereby raising d which is secured to'the lower exposed face'of the base shown. This bottom plateis provided with a U-shaped' cavity 111, partly divlded by a straight. rib 112 terminating in acentral boss 1 13; A sponge rubber filler 114 fits the valve from the seat 29. Thisaction' serves to regu-. late the pressure of vaporized fuel discharged through outlet 64. The pressure sensing opening 84in the plate to causeithe plunger 103 to raise against the action of the spring 106, thereby lifting the lower end of the :plunger 103' away from the upper'end of the diaphragm shank 45. Should the suction pressure drop below 5 inches of mercury thespring 106 acts to move the plunger 103 downward into contact withthe part 45,

supplementing the force; of the sprin'g90, and tending to open the valve 40.. Atfull power of the engine, correspondingflto zerosuction pressure, the pressure of vaporizedfuel at the outlet 64 i's increased to about 2% psi.

, gage. This serves torichentheairfuel mixture forheavy loadjconditionsp Y I a V The porous disk--66 is formed of non-metallic flexible foraminous material having a relatively rouglrexternal The myriad interstices and the rough surface the surface toward the outlet 64, and allows themto be vaporized" by contact, with the gas before reaching the outlet 64; The. disk is compressedas illustrated in FIG- URE 2 between the cover plate 67 and theuppe'r ends of the labyrinth walls. 30, 31, 55, and 62 (see FIGURE 3). The disk 66' thus formsa' seal between adjacent V parts of thelabyrinth' paths. 50

The presence of water in-the passages in the base 25 presents the danger of breakage of the base member by forces developed if the water should freeze. This possibili'ty'is present when the.,vehicle. is operated in cold climates or ifwater circulation is interrupted while engine operating. Accordingly to prevent breakage by expans1on of ice under freezing conditions, I provide expansion means which are normally .inactive but which function.

under the abnormally high pressure produced by ice formation 1o allow additional space for exp'ansionand thus to prevent damage. I provide a metalbottom plate 110 member 25 by means of suitable threaded fastenings, not

loosely in the cavity. A gasket 1 15 covering the entire area of the bottom plate 110 rests upon this filler 114 and upon the rib 112 and boss 113.; A relief port 116 in the cavity l'll'extends to atmosphere; The rubber filler 114 resists the normal water pressure in thechannels' 91, 92,

and v93,'but deforms under extremely high pressures as developed by ice formationxto conform more closely to the shape of'the cavity 111. Uponmelting of the ice, the rubber filler 114 returns to its previous shape within the cavity 111.'

As shown in FIGURE 7 the diaphragm 70 is provided with a tab-like projection 118 and this projection is adapted to cover the recess 119a provided in the outer Wall of the base member 125. To connect diaphragm shank 45 with the slotted end of the valve lever 33, the diaphragm is placed on the base member 25 in a position one-quarter turn from its normal operating position. The lug 46 will then pass downward through the slot 43 in the valve lever 33. Subsequent turning of the diaphragm 70 to bring the tab 118 into registry with the recess 119a serves to prevent disassembly of the diaphragm shank 45 and valve lever 33.

The mixer 15 includes a housing 119 having concentric upstanding walls 120 and 121 defining a generally annular space 122 therebetween. The air inlet 17 communicates with this space 122 and the vortex-preventing rib 123 connects the walls and interrupts the annular space only to the extent of its width. A boss 124 around the fuel inlet 125 also projects into the annular space 122 to some extent, but the space 122 between the walls 121 and 120 remains essentially annular.

The upper end of the inner circular wall 121 terminates in an annular seat 126 and an air valve member 127 cooperates with this seat to control the flow of air from the annular space 122 into the interior of the wall 121 and into the discharge opening 128.

The interior of the upper portion of the inner wall 121 is provided with a bore 129 for sliding reception of the outer edges of the four lugs 130 which extend radially from the air valve member 127. These lugs guide the valve member 127 for axial movement and prevent formation of a vortex. The outer surface 131 of the air valve member 127 converges downward from the direction of flow and this surface is interrupted by the four bosses 132 and the guide lugs 130 which extend from them. The bosses 132 contain the axially extending openings 133 which project through the air valve member 127 from top to bottom The air valve member is provided with a downward facing cup-shaped recess 135 which is centrally positioned and which flares outward in the direction of flow. A stationary hollow post 136 projects upward into this recess and the post carries a bushing 137 at its upper end which provides a fuel valve seat 138. A fuel valve element 139 including a resilient ring 148 is fixed centrally of the air valve member 127 by deforming the upper end 141 thereof. An upper stern on the valve plug 133 extends through aligned apertures in the air valve member 137 and in the diaphragm backing plate 142 of the flexible diaphragm 143. The deformed upper end 141 of this stem thus serves to clamp the metal plug 139, resilient ring 140, air valve member 172, backing plate 142 and washer 144 together so that these parts move as a unit.

A loose floating ring 145 is carried on the horizontal shoulder 146 of the air valve member 127 and this ring is adapted to rest on the seat 126 to form a seal. The outer peripheral portion of the circular diaphragm 143 is clamped between the housing 119 and the bonnet 147 by means of threaded fastenings 148 but the inner portion of the diaphragm 143 is loosely received in the annular space between the floating ring 14-5 and the diaphragm backing plate 142 and hence floats laterally for perfect alignment of the air and fuel valves. The bonnet 147 cooperates with the diaphragm 143 to define a space 148 and this space communicates through apertures 149 in the backing plate 142 and through the axial openings 133 in the air valve member 127 with the mixing chamber within the wall 121 and leading to the discharge opening 128. Accordingly, the upper surface of the diaphragm 143 is subjected to pressure in the discharge opening 128, while the lower face is subjected to pressure of the air inlet 17. A coil spring 150 within the space 148 acts to move the air valve member 127 toward closed position.

The fuel valve element 139 has a cylindrical portion 152 adjacent its upper end and a series of tapered sections 153, 154, 155 and 156 extending toward the bottom end thereof. In addition, diametrically positioned slots 158 which extend axially of the valve element are provided which interrupt the cylindrical and tapered external surfaces. The plug element 139 moves axially within the bore 160 of the stationary bushing 137 to control the rate of flow of vaporized fuel from the inlet 125 into the central cup-like cavity 135 in the air valve member 127. Vaporized fuel passes from the inlet 125 through the horizontal tube 161 and hollow post 136. The tube 161 and the hollow post 136 are positioned within the wall 121 of the housing 119.

From this description it will be understood that the air valve member 127 and the fuel valve element 139 move axially as a unit to control the flow of air and vaporized fuel into the mixing chamber 157 within the wall 121 and into the discharge opening 128. Intimate and thorough mixing of vaporized fuel and air is achieved because the vaporized fuel passes downward in an annular expanding ring emerging from the flaring surface of the recess 135, while air passes downward and inward along the converging surface 131 of the air valve member 127. Vortex action of the air is prevented by the rib 123 and the fins 130. A reduction in pressure within the discharge opening 128 is refiected through the openings 133 into the space 148 above the diaphragm 143 with the result that the diaphragm lifts the air valve member 127 and fuel valve element 129 upward against the action of the coil spring 150. Conversely, an increase in pressure in the discharge opening 128 causes both the air valve member 127 and fuel valve element 139 to move downward to reduce the rate of flow.

Means are provided for adjusting the richness of the fuel mixture throughout the speed range of the engine. As shown in the drawings this means includes a bypass 162 between the air inlet 17 and the space 148 above the diaphragm 143, together with a valve 163 to restrict the bypass to any desired degree. This valve may take the form of a tubular member 164 having a port 165 which may be aligned to any extent desired with a bore 166 communicating with the air inlet 17. Turning of the exposed head 167 of the tubular member 164 serves to provide any degree of restriction desired. A reference mark 168 on the head may cooperate with indicia 169 on the bonnet 147. The effect of the valved bypass 162 is to supplement the force of the spring 150 tending to close the air valve and fuel valve, and because the gas is sup plied at a pressure greater than atmospheric pressure, the gas flow is reduced more than the air flow, thus serving to lean the mixture.

Additional means are provided for adjusting the richness of fuel mixture at idle speed and as shown on the drawings this means takes the form of a smooth bore 170 extending through the inner wall 121 (see FIGURE 11). This opening establishes communication from the annular air space 122 to the discharge opening 128. A machine screw 1'71 threaded in the boss 172 provides a means of restricting the opening 170, and a spring 173 encircling the exposed portion of the machine screw serves to hold it in selected position. Maximum richness of mixture is achieved when the restriction is greatest. This adjustment is principally effective at idle speed.

Considering the over-all fuel system, it is important that the fuel supply be positively shut off when the engine ceases to operate, to prevent leakage and avoid danger of a fire. This shut off is accomplished by means of a conventional type electrically operated valve 11 connected in series with a battery 175 and an electric switch 176. The electric switch 176 may be mounted in a pocket 177 provided in a cap 178 for the bonnet 14-7. The switch terminals 179 and 180 project out of the pocket 177. Internal mechanism generally designated 181 serves to close an electric path between the terminals 179 and 180, whenever the contact element 182 is actuated.

A diaphragm 183 is clamped between the cap 178 and l bonnet 147 and is positioned between circular metal plates 1-84 and 1-85 clamped to: the diaphragm, 183 by means of the central fastener 186." A cavity 187 is formed below I pressure through port 190. A stationary 'p ost 192'is located within the chamber 187 in an off-center position 7 between the'central fastener 186-and the location of the switch element 182. pressure in the discharge passage 128 is lower than atmosphericpressure and therefore theldiaphragm 183 is drawn downwardinto the cavity and tilted byreason of its'contact with the stationary guidepostj192, The tiltinglaction causes the upper plate 184to engage. the element 182 of the switch 186,,thereby closing the. circuit. through the battery 175 and electrically operated valve 11, and the leverages produce a force-multiplying action. Closing of the'eleetric circuit opens the 'valve to allow flow of liquid fuel therethrough. When the "engine ceases opera.- tion the pressures across the diaphragm 183 are equalized and' the resilient diaphragm returns to a generally horizontal position, separating the upper plate 184 from the switchelement-ISZ. The electriccircuit is broken and the valve 11 is closed by an internal spring, not sho n Having fully described my invention, it is ,to be under- When, the engine is running, the' va'porized by contact with theagas-be fore the droplets reach the outlet. 1 a

3. ha vaporizerthe combination of: a base member havingan'inlet forliquid and .an .outlettor gasfwalls on the base member providing a labyrinth passageway leading to'the outlet, means to heat said 'Walls, an unheated cover plate for, said base member, and an unheated foraminous element having a rough surface and myriad interstices, said element being compressed between the cover plate and said "walls to form a -seal and defining a bound- :aryjsu'rtace of the labyrinth passage, said elementacting tofimpede progress of droplets of liquid moving thereon 7 toward said outlet'so that the droplets maybe vaporized by contact 7 with the gas before the droplets reach the outlet. .f I

, 4.In a vaporizer and pressure regulator for liquid petroleum gas, the combination of: 'a base member having an inlet for liquid and an outlet for gas, walls on the base member providing a passageway from the inlet to the )Olltifit, valve means withinthe base member operatively interposed between the inlet andrthe outlet for regulating flow from the inlet,.means for passing a heating liquid in contact w1th said walls, an unheated cover plate for said base member, and an unheated flexible foraminous element having a' rough surface and myriad interstices, said element being compressed between'the cover plate and said walls to form -a seal and defininga boundary surface .ot the labyrinth passage,-said element acting to impede progress of droplets of liquid movingthereon toward said outletso that the droplets may be vaporized by contact withlthe gasbefore thedroplets reach the outlet.

stood thatI do not wish to be limited to the details herein set forth but my invention is of the full scope of the I appended claims; V I claim: i o q 7 v 1. In a vaporizer, thecombinationof: .a heated metal '5. "The combination ofclaim 4 in which said flexible forarninous element-is substantially coextensive with the cover 1 plate.

6. In a vaporizer, the combination of: a base member havingwalls defining a labyrinth passageway, means for base member having an inlet forliquid and anoutlet for" gas; said member having curved wa'lls providing ,a labyrinth passageway leading to said outlet, an unheated metal cover plate for said member, an unheatedflexible spongy' 40' disk-interposed betweenlsaidmember and said'cover plate and forrning one boundary surface of saidllabyrinth, passageway, thespongy disk having a rough porous sur face to impede progress ofxdropletsof liquid mo-vingthereon toward the outlet, so that the droplets mayi-beva'porized-j heatingithejwalls, an'unh'eated cover plate for said base member, and an unheated flexible foraminous nonmetallic -'element-having' a roughysurface and myriad interstices, said element being compressed between said cover plate and said walls to form a seal along said walls, the rough surfia'ce'of said element defining a boundarysurface of the by contact with-the gas before the vdroplets;reach the outlet.

' 2. In avaporizer, the combination of; ,a heated, metal a base member 'having an inlet for liquid andan outlet for gas, said member having curv'ed walls providing a labyrinth passageway leading to said outlet, means forl cire culating a heating fluid within said walls, an unheated metal cover plate for said member, an unheated flexible spongy disk interposed between said" member andsaid cover plate and forming one boundary surface of said labyrinth passageway, the spongy disk forming a seal between said members and having a rough porous sur face to impede progress of droplets of liquid moving labyrinth passage,'said element acting to impede progress 10f droplets of liquid moving thereon toward said .outlet so that the droplets may be vaporized by contact with the ,gas before the droplets reach the outlet.

References: Cited bytheExaniiner' UNITED STATES PATENTS 11,353,288 9/20 Stokes 48-180 2,272,341 2/42 -Ho1zapfe1 48'l06 I 2,752,758 7/ 56 Tann 25 7241 2,832,264 4/58' Pilling ,137"340 2,832,325 4/58' Liebel 123-3021 2,926,682 '3/60' Zonkeretial 137-240 2, 942,591' 6/60 Meurer,; 123'30.21

.MORRIS o. WOLK, Primary Examiner, 'GE'ORGED. M-ITCHELL,Examiner. 

1. A VAPORIZER, THE COMBINATION OF: A HEATED METAL BASE MEMBER HAVING AN INLET FOR LIQUID AND AN OUTLET FOR GAS, SAID MEMBER HAVING CURVED WALLS PROVIDING A LABYRINTH PASSAGEWAY LEADING TO SAID OUTLET, AN UNHEATED METAL COVER PLATE FOR SAID MEMBER, AN UNHEATED FLEXIBLE SPONGY DISK INTERPOSED BETWEEN SAID MEMBER AND SAID COVER PLATE AND FORMING ONE BOUNDARY SURFACE OF SAID LABYRINTH PASSAGEWAY, THE SPONGY DISK HAVING A ROUGH POROUS SURFACE TO IMPEDE PROGRESS OF DROPLETS OF LIQUID MOVING THEREON TOWARD THE OUTLET, SO THAT THE DROPLETS MAY BE VAPORIZED BY CONTACT WITH THE GAS BEFORE THE DROPLETS REACH THE OUTLET. 